A fully differentiated cell is defined by the genes it expresses and, ultimately, by its physiological functions. This normal pattern of gene expression, or transcriptome, is altered in a diseased state such that function is perturbed, growth is deregulated, and communication with other cells affected. The question is, how are these abnormal expression patterns established and maintained in the absence of genetic mutations? We propose that epigenetic modifications on the genome, and specifically histone methylation, impact gene expression changes in diseased tissues. To explore this hypothesis, we must first understand how epigenetic modifications are imprinted during development of the embryo, as cell lineages decisions are made. Previously, the PI has identified Pax2 as a critical DNA binding protein in the renal epithelial lineage. The lab then discovered PTIP as an adaptor protein that links Pax2 to a histone methylation complex to imprint positive epigenetic marks on target genes. In this application, Aim 1 will use chromatin immunoprecipitation, next generation sequencing, and specific strains of genetically altered mice to map the sites of Pax2/PTIP interactions with the genome and to correlate this with gene expression patterns. Furthermore, we have the first real evidence that altering a histone methylation pathway in a cell specific manner can lead to chronic renal disease. In Aim 2, we will define the role of PTIP and histone methylation in renal interstitial fibrosis and correlate this with TGF- signaling pathways that are known to mediate fibrosis. While there are many correlations of epigenetic changes in cancer and other disease states, our studies will address for the first time whether epigenetic modifications can directly initiate a disease state in the absence of other mutations or environmental insults. Our preliminary data strongly suggests that they can.